CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows from Operating Activities:
Net income	$ 364	$ 90
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	653	656
Amortization of deferred financing costs	14	18
Amortization of intangible assets in non-utility cost of revenues	12	0
Deferred income taxes	(21)	(12)
Unrealized gain on marketable securities	(147)	(23)
Loss on indexed debt securities	154	272
Write-down of natural gas inventory	3	1
Equity in earnings of unconsolidated affiliates, net of distributions	12	(9)
Pension contributions	(29)	(64)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	463	232
Inventory	10	52
Accounts payable	(594)	(246)
Taxes receivable	(69)	(39)
Fuel cost recovery	78	69
Non-trading derivatives, net	(71)	64
Margin deposits, net	(12)	(9)
Interest and taxes accrued	(88)	(64)
Net regulatory assets and liabilities	(77)	57
Other current assets	20	(4)
Other current liabilities	(156)	(13)
Other assets	76	(3)
Other liabilities	(30)	60
Other operating activities, net	9	8
Net cash provided by operating activities	574	1,093
Cash Flows from Investing Activities:
Capital expenditures	(1,169)	(697)
Acquisitions, net of cash acquired	(5,987)	0
Distributions from unconsolidated affiliate in excess of cumulative earnings	0	30
Proceeds from sale of marketable securities	0	398
Increase in notes receivable–affiliated companies	(4)	0
Other investing activities, net	11	2
Net cash used in investing activities	(7,149)	(267)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	0	(39)
Proceeds from (payments of) commercial paper, net	2,221	(1,188)
Proceeds from long-term debt, net	1,721	997
Payments of long-term debt	(1,077)	(230)
Long-term revolving credit facility	135	0
Debt issuance costs	(9)	(35)
Payment of dividends on Common Stock	(288)	(240)
Payment of dividends on Preferred Stock	(60)	0
Distribution to ZENS note holders	0	(16)
Other financing activities, net	(14)	(5)
Net cash provided by (used in) financing activities	2,629	(756)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(3,946)	70
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	4,278	296
Cash, Cash Equivalents and Restricted Cash at End of Period	332	366
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income	127	153
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	351	495
Amortization of deferred financing costs	5	6
Deferred income taxes	(27)	(38)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(56)	(107)
Accounts receivable/payable–affiliated companies	(35)	78
Inventory	(7)	(6)
Accounts payable	2	(6)
Taxes receivable	(8)	(23)
Non-trading derivatives, net	(25)	0
Interest and taxes accrued	(34)	(45)
Net regulatory assets and liabilities	(69)	(59)
Other current assets	18	4
Other current liabilities	(4)	(11)
Other assets	10	2
Other liabilities	(3)	2
Other operating activities, net	(5)	(2)
Net cash provided by operating activities	240	443
Cash Flows from Investing Activities:
Capital expenditures	(514)	(441)
Increase in notes receivable–affiliated companies	(794)	(26)
Other investing activities, net	(3)	(1)
Net cash used in investing activities	(1,311)	(468)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	696	398
Payments of long-term debt	(242)	(230)
Decrease in notes payable–affiliated companies	(1)	(60)
Dividend to parent	(40)	(63)
Contribution from parent	590	0
Debt issuance costs	(8)	(4)
Other financing activities, net	(1)	1
Net cash provided by (used in) financing activities	994	42
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(77)	17
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	370	274
Cash, Cash Equivalents and Restricted Cash at End of Period	293	291
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income	166	166
Less: Income from discontinued operations, net of tax	0	96
Income from continuing operations	166	70
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	153	145
Amortization of deferred financing costs	4	4
Deferred income taxes	20	9
Write-down of natural gas inventory	3	1
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	554	339
Accounts receivable/payable–affiliated companies	(11)	(14)
Inventory	26	58
Accounts payable	(442)	(248)
Fuel cost recovery	78	69
Non-trading derivatives, net	(62)	61
Margin deposits, net	(12)	(9)
Interest and taxes accrued	(31)	(20)
Net regulatory assets and liabilities	15	92
Other current assets	7	7
Other current liabilities	(21)	8
Other assets	(2)	4
Other liabilities	3	52
Other operating activities, net	1	0
Net cash provided by operating activities from continuing operations	449	628
Net cash provided by operating activities from discontinued operations	0	118
Net cash provided by operating activities	449	746
Cash Flows from Investing Activities:
Capital expenditures	(322)	(230)
Increase in notes receivable–affiliated companies	(66)	0
Other investing activities, net	2	3
Net cash used in investing activities from continuing operations	(386)	(227)
Net cash provided by investing activities from discontinued operations	0	30
Net cash used in investing activities	(386)	(197)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	0	(39)
Proceeds from (payments of) commercial paper, net	22	(333)
Proceeds from long-term debt, net	0	599
Decrease in notes payable–affiliated companies	0	(570)
Dividend to parent	(103)	(211)
Contribution from parent	0	0
Debt issuance costs	0	(5)
Other financing activities, net	(2)	(1)
Net cash used in financing activities from continuing operations	(83)	(560)
Net cash provided by financing activities from discontinued operations	0	0
Net cash provided by (used in) financing activities	(83)	(560)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(20)	(11)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	25	12
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 5	$ 1